With 6x2= 12 railway freight cars, 15x2=30 cars, which is exactly 360x2=720 tons.

Eight railway cars and 10 cars are exactly 440 tons.

With 8x3=24 railway carriages, 10x3=30 carriages, it is exactly 440x3= 1320 tons.

Leather in each row: (1320-720)/(24-12) = 50 (ton)

Each vehicle: (360-6x50)/ 15=4 (ton)